1. Field of the Invention
The present invention relates to a solid-state image pickup apparatus such as a digital camera.
Priority is claimed on Japanese Patent Application No. 2008-164203 filed on Jun. 24, 2008, the contents of which are incorporated herein by reference.
2. Description of Related Art
Solid-state image pickup apparatuses using a variety of image pickup devices such as a MOS-type image pickup device and a CCD-type image pickup device have been proposed and put to practical use. Furthermore, solid-state image pickup apparatuses provided with a MOS-type image pickup device include an amplification-type solid-state image pickup apparatus. The amplification-type solid-state image pickup apparatus includes: an electric charge generation device; and a pixel signal generation device which generates a pixel signal in accordance with a signal charge generated by the electric charge generation device, in which the pixel signal generation device has pixels configured as an amplification-type solid-state image pickup device (APS, Active Pixel Sensor), each pixel having a drive transistor for amplification. Many of the (C)MOS-type solid-state image pickup apparatuses have such a configuration.
In addition, column-ADC-system solid-state image pickup apparatuses in which an A/D conversion (analog/digital) function is embedded in a column portion have also been developed and commercialized. Known A/D conversion systems include a successive approximation register (SAR) A/D conversion system, a single-slope A/D conversion system, and a cyclic A/D conversion system. Furthermore, a column-ADC (A/D Converter)-system solid-state image pickup apparatus as follows has also been proposed (for example, Japanese Unexamined Patent Publication, First Publication No. 2006-270293). In this ADC system, a column portion has a time-to-digital converter (TDC) with a function of converting voltage to frequency in accordance with a signal from a pixel. Japanese Unexamined Patent Publication, First Publication No. 2006-270293 says that it is possible to A/D-convert a signal from a pixel with comparative ease and a high S/N by use of a TDC.